1A student has 3 shirts and 2 pairs of trousers. How many different shirt-trouser outfits can the student wear?
Principles of counting
Easy
A.6 outfits
B.9 outfits
C.8 outfits
D.5 outfits
Correct Answer: 6 outfits
Explanation:
By the multiplication principle, the number of outfits is .
Incorrect! Try again.
2A cafe offers 4 types of juice and 3 types of milkshake. If one drink is selected, how many choices are available?
Principles of counting
Easy
A.4 choices
B.7 choices
C.12 choices
D.3 choices
Correct Answer: 7 choices
Explanation:
By the addition principle, the number of choices is .
Incorrect! Try again.
3In how many ways can 2 students be selected from a group of 4 students?
Problems based on selection
Easy
A.12 ways
B.6 ways
C.4 ways
D.8 ways
Correct Answer: 6 ways
Explanation:
Selection does not consider order, so the answer is .
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4How many ways can one fruit be selected from 5 different fruits?
Problems based on selection
Easy
A.10 ways
B.4 ways
C.1 way
D.5 ways
Correct Answer: 5 ways
Explanation:
Any one of the 5 different fruits can be selected, giving ways.
Incorrect! Try again.
5In how many ways can 3 different books be arranged in a row?
Problems based on arrangement
Easy
A.6 ways
B.9 ways
C.8 ways
D.3 ways
Correct Answer: 6 ways
Explanation:
The number of arrangements is .
Incorrect! Try again.
6In how many ways can 2 different prizes be awarded to 2 students if each student receives one prize?
Problems based on arrangement
Easy
A.1 way
B.4 ways
C.2 ways
D.3 ways
Correct Answer: 2 ways
Explanation:
The two different prizes can be arranged among the students in ways.
Incorrect! Try again.
7How many two-digit numbers can be formed using the digits 1, 2, and 3 without repetition?
Problems based on numbers
Easy
A.9 numbers
B.3 numbers
C.6 numbers
D.8 numbers
Correct Answer: 6 numbers
Explanation:
There are 3 choices for the tens place and 2 remaining choices for the units place, so .
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8How many one-digit even numbers can be formed using the digits 1, 2, 3, 4, and 5?
Problems based on numbers
Easy
A.2 numbers
B.5 numbers
C.1 number
D.3 numbers
Correct Answer: 2 numbers
Explanation:
The available even digits are 2 and 4, so 2 such numbers can be formed.
Incorrect! Try again.
9How many distinct arrangements can be made using all the letters of the word "CAT"?
Problems based on words
Easy
A.9 arrangements
B.8 arrangements
C.3 arrangements
D.6 arrangements
Correct Answer: 6 arrangements
Explanation:
All 3 letters are different, so the number of arrangements is .
Incorrect! Try again.
10How many distinct arrangements can be made using all the letters of the word "MOM"?
Problems based on words
Easy
A.6 arrangements
B.4 arrangements
C.2 arrangements
D.3 arrangements
Correct Answer: 3 arrangements
Explanation:
The letter M occurs twice, so the number of distinct arrangements is .
Incorrect! Try again.
11How many line segments are determined by 4 distinct points if no three points are collinear?
Geometric applications
Easy
A.12 segments
B.4 segments
C.8 segments
D.6 segments
Correct Answer: 6 segments
Explanation:
Each line segment is determined by selecting 2 points, so the number is .
Incorrect! Try again.
12In how many ways can 4 people sit around a circular table?
Circular arrangement
Easy
A.6 ways
B.12 ways
C.24 ways
D.4 ways
Correct Answer: 6 ways
Explanation:
The number of circular arrangements of 4 people is .
Incorrect! Try again.
13What is the probability of a certain event?
Concept of probability
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
A certain event always occurs, so its probability is .
Incorrect! Try again.
14What type of event has a probability equal to ?
Classification of events
Easy
A.Equally likely event
B.Impossible event
C.Certain event
D.Complementary event
Correct Answer: Impossible event
Explanation:
An impossible event cannot occur, so its probability is .
Incorrect! Try again.
15A fair coin is tossed once. What is the probability of getting a head?
Problems based on coins
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
There are two equally likely outcomes, H and T, and one of them is a head. Thus, the probability is .
Incorrect! Try again.
16Two fair coins are tossed together. What is the probability of getting two tails?
Problems based on coins
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The equally likely outcomes are HH, HT, TH, and TT. Only TT gives two tails, so the probability is .
Incorrect! Try again.
17A fair six-sided die is rolled once. What is the probability of obtaining an even number?
Problems based on dice
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The even outcomes are 2, 4, and 6. Therefore, the probability is .
Incorrect! Try again.
18A fair six-sided die is rolled once. What is the probability of obtaining a number greater than 4?
Problems based on dice
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The favorable outcomes are 5 and 6, so the probability is .
Incorrect! Try again.
19One card is drawn from a standard deck of 52 cards. What is the probability of drawing an ace?
Problems based on cards
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
A standard deck has 4 aces, so the probability is .
Incorrect! Try again.
20A card is known to be a face card from a standard deck. What is the probability that it is a king?
Conditional probability
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
There are 12 face cards: 4 jacks, 4 queens, and 4 kings. Thus, the conditional probability is .
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21A security code consists of two distinct letters selected from 5 available letters, followed by three digits. Digits may be repeated. How many security codes are possible?
Principles of counting
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The letters can be selected and arranged in ways, while the digits have possibilities. Thus, the total is .
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22A committee of 5 is to be selected from 8 men and 6 women. In how many ways can the committee contain at least 3 women?
Problems based on selection
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The valid cases contain 3, 4, or 5 women. Hence, the number is .
Incorrect! Try again.
23Seven distinct books are arranged on a shelf. If three particular mathematics books must remain together, how many arrangements are possible?
Problems based on arrangement
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Treat the three mathematics books as one block. The block and four other books can be arranged in ways, and the books inside the block in ways. Therefore, the answer is .
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24How many four-digit even numbers can be formed using the digits without repetition?
Problems based on numbers
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
If the last digit is , there are numbers. If it is , , or , there are numbers. The total is .
Incorrect! Try again.
25In how many distinct arrangements of the letters of the word EDUCATION do all five vowels occur together?
Problems based on words
Medium
A.
B.
C.
D., after separately arranging every vowel and consonant
Correct Answer:
Explanation:
Treat the five vowels as one block. This block and the four consonants can be arranged in ways, while the vowels can be arranged in ways. Thus, the number is .
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26Ten points lie in a plane, with no three points collinear. How many triangles can be formed using these points as vertices?
Geometric applications
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Any selection of three points forms a triangle because no three are collinear. Therefore, the number of triangles is .
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27Six people, including Arun and Beena, sit around a circular table. In how many arrangements are Arun and Beena not adjacent?
Circular arrangement
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
There are total arrangements. If Arun and Beena are together, there are arrangements. Therefore, the required number is .
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28An integer is selected uniformly at random from to . What is the probability that it is divisible by or ?
Concept of probability
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
There are multiples of , multiples of , and multiples of both. Thus, the favorable count is , giving probability .
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29One card is drawn from a standard deck. Let be the event that the card is a king and the event that it is a queen. How are and classified?
Classification of events
Medium
A.Both mutually exclusive and exhaustive
B.Independent because kings and queens have equal probabilities
C.Exhaustive but not mutually exclusive
D.Mutually exclusive but not exhaustive
Correct Answer: Mutually exclusive but not exhaustive
Explanation:
A single card cannot be both a king and a queen, so the events are mutually exclusive. Their union does not include the other 44 cards, so they are not exhaustive.
Incorrect! Try again.
30Four fair coins are tossed simultaneously. What is the probability of obtaining exactly two heads?
Problems based on coins
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
There are equally likely outcomes. Exactly two heads can occur in ways, so the probability is .
Incorrect! Try again.
31Two fair dice are rolled. What is the probability that at least one die shows a ?
Problems based on dice
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The probability that neither die shows is . Therefore, the required probability is .
Incorrect! Try again.
32One card is drawn from a standard deck of 52 cards. What is the probability that it is a red face card?
Problems based on cards
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Each red suit has three face cards, giving red face cards. The probability is .
Incorrect! Try again.
33Two cards are drawn successively without replacement from a standard deck. Given that the first card is an ace, what is the probability that the second card is also an ace?
Conditional probability
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
After one ace has been drawn, aces remain among cards. Thus, the probability is .
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34There are 4 routes from city to city and 3 routes from city to city . A traveler goes from to through and returns through without using either return route used on the outward journey. How many round trips are possible?
Principles of counting
Medium
A.
B.
C., including trips that reuse exactly one outward route
D.
Correct Answer:
Explanation:
The outward journey has choices. For the return, there are choices from to and from to . Hence, the total is .
Incorrect! Try again.
35Four students are selected from a group of 10. If two particular students cannot both be selected, how many selections are possible?
Problems based on selection
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
There are total selections. The two particular students appear together in selections. Therefore, the required number is .
Incorrect! Try again.
36Five boys and four girls are arranged in a row so that no two girls are adjacent. How many arrangements are possible?
Problems based on arrangement
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Arrange the boys in ways. There are six gaps around them, and four gaps are selected for the girls in ways. The girls can be arranged in ways, giving .
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37How many four-digit odd numbers greater than can be formed using the digits without repetition?
Problems based on numbers
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
If the thousands digit is , , or , there are numbers. If it is or , there are . The total is .
Incorrect! Try again.
38How many distinct arrangements of the letters of BALLOON have the two letters L together?
Problems based on words
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Treat LL as one unit. The six units are LL, B, A, O, O, and N, with O repeated twice. Therefore, the number of arrangements is .
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39Two cards are selected simultaneously from a standard deck. What is the probability that exactly one of them is an ace?
Problems based on cards
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Select one ace and one non-ace in ways. Since there are two-card hands, the probability is .
Incorrect! Try again.
40Factory supplies of a company's components and has a defect rate. Factory supplies and has a defect rate. If a selected component is defective, what is the probability that it came from factory ?
Conditional probability
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The defective probabilities from and are and . Thus, .
Incorrect! Try again.
41How many 8-character passwords can be formed using uppercase English letters and digits if the first character must be a letter, exactly two positions must contain distinct digits, and repetition of letters is allowed?
Principles of counting
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The two digits must occupy two of the last seven positions: . They can be arranged in ways, and the six letter positions have choices.
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42A committee of 5 is chosen from 7 men and 6 women. How many committees contain at least two women and do not contain both a particular man and a particular woman?
Problems based on selection
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Committees with at least two women: . Those containing both specified people number . Hence the answer is .
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43How many distinct arrangements of the letters of have no two 's adjacent?
Problems based on arrangement
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Arrange in ways. These create four gaps, and three of them must receive the identical 's: . Thus the total is .
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44How many 5-digit numbers with distinct digits are greater than and divisible by ?
Problems based on numbers
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
If the final digit is , there are possibilities. If it is , there are . Their sum is .
Incorrect! Try again.
45How many distinct arrangements of the letters of have no two 's adjacent?
Problems based on words
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Arrange the non- letters in ways. They create eight gaps, and four gaps are selected for the 's: . Therefore, the total is .
Incorrect! Try again.
46Eight points lie on a circle. Assuming no three chords meet at the same interior point, how many interior intersection points are formed by the chords joining pairs of points?
Geometric applications
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Each interior intersection is determined by choosing four points, whose four chords contain one crossing pair. Hence the number is .
Incorrect! Try again.
47Eight distinct people are seated around a circular table. In how many arrangements, considered identical under rotation but not reflection, are two specified people not adjacent?
Circular arrangement
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
There are circular arrangements. When the specified people are adjacent, treat them as a block, giving arrangements. The required number is .
Incorrect! Try again.
48Two fair dice are rolled. What is the probability that their sum is prime and their product is even?
Concept of probability
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Prime sums correspond to outcomes. Among these, only has an odd product, so outcomes qualify. Thus the probability is .
Incorrect! Try again.
49On a fair die, let be the event that the outcome is prime and the event that it is even. How should and be classified?
Classification of events
Hard
A.Mutually exclusive and exhaustive, with no dependence relation
B.Exhaustive but not mutually exclusive, and independent
C.Neither mutually exclusive nor exhaustive, and dependent
D.Mutually exclusive but not exhaustive, and independent
Correct Answer: Neither mutually exclusive nor exhaustive, and dependent
Explanation:
and overlap at , while their union omits . Also, , so they are dependent.
Incorrect! Try again.
50Five fair coins are tossed. Given that at least two heads occur, what is the probability of obtaining exactly three heads?
Problems based on coins
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
There are outcomes with exactly three heads. The conditioning event has outcomes. Therefore, the conditional probability is .
Incorrect! Try again.
51Three fair dice are rolled. What is the probability that the maximum is exactly and the sum is ?
Problems based on dice
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
There are triples from summing to , but one is and has maximum . Thus outcomes qualify, giving .
Incorrect! Try again.
52A 5-card hand is dealt from a standard 52-card deck. What is the probability that it contains exactly two aces and at least one king?
Problems based on cards
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Choose exactly two of the four aces. From the remaining cards, choose three cards containing at least one king: .
Incorrect! Try again.
53An urn contains 5 red and 4 blue balls. Two balls are drawn without replacement. Given that at least one ball is red, what is the probability that both balls are red?
Conditional probability
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The favorable selections number . The conditioning event has selections. Hence the probability is .
Incorrect! Try again.
54How many arrangements of the letters of have all five vowels nonadjacent and have appearing before ?
Problems based on words
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Arrange the four consonants in ways and place the five vowels in the five resulting gaps in ways. Exactly half of the consonant orders have before , giving .
Incorrect! Try again.
55How many 5-digit numbers can be formed from the digits without repetition and are divisible by ?
Problems based on numbers
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The possible distinct final two-digit blocks divisible by are in number. For each block, the first three positions can be filled in ways, accounting for the restriction that the first digit cannot be zero. Thus the total is .
Incorrect! Try again.
56In a convex polygon with vertices, how many ways can three diagonals be selected so that no two selected diagonals share an endpoint?
Geometric applications
Hard
A.
B.
C.
D.The count is obtained by selecting six vertices and pairing them while excluding every pair that forms a side; this gives valid selections.
Correct Answer:
Explanation:
The number of ways to choose three pairwise vertex-disjoint diagonals in a convex -gon is , obtained by inclusion-exclusion over the forbidden side pairings.
Incorrect! Try again.
57A fair die is rolled twice. Let be the event that the first result is even and the event that the second result is even. Which statement is correct?
Classification of events
Hard
A.They are independent but not mutually exclusive
B.They are exhaustive and mutually exclusive
C.They are mutually exclusive but not independent
D.They are dependent because both events involve even outcomes
Correct Answer: They are independent but not mutually exclusive
Explanation:
The two rolls are independent, so . They are not mutually exclusive because both can occur simultaneously.
Incorrect! Try again.
58Four fair coins are tossed. Given that the first and fourth coins show different results, what is the probability of obtaining at least two heads in total?
Problems based on coins
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
When the first and fourth coins differ, they contribute exactly one head. At least two heads therefore requires at least one head among the middle two coins, which has probability .
Incorrect! Try again.
59Two fair dice are rolled. Given that their sum is at least , what is the probability that they show the same number?
Problems based on dice
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
There are outcomes with sums . The doubles among them are and , so the probability is .
Incorrect! Try again.
60A 5-card hand is selected from a standard deck. Given that the hand contains at least one ace, what is the probability that it contains exactly two aces?
Problems based on cards
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The numerator counts hands with exactly two aces. The conditioning event contains all hands except those with no aces, numbered .
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